Partition recovery method

ABSTRACT

There is provided a method and system of maintaining partition information relating a computer disc drive. The method includes detecting partition information which is located in the first sector of a partition of a disc drive and determining if it is valid, and comparing the valid partition information with a corresponding duplicate of the partition information which is located in a reserved area. For valid partition information which is the same as the corresponding duplicate of the partition information, a standard booting procedure for the computer is allowed to continue. For valid partition information which is not the same as the corresponding duplicate partition information, valid partition information is stored in the reserved area. For partition information which is not valid, the invalid partition information is replaced with corresponding duplicate partition information which is valid.

RELATED APPLICATIONS

This application is related to and claims priority from U.S. ProvisionalApplication Ser. No. 60/218,024, filed on Jul. 12, 2000, and is also aContinuation-in-Part of U.S. patent application Ser. No. 09/901,501filed on Jul. 9, 2001.

FIELD OF THE INVENTION

This invention relates to partition recovery. It relates particularlybut not exclusively to a method of maintaining partition informationrelating to a disc drive and to a system for maintaining informationrelating to partitions in disc drives.

BACKGROUND OF THE INVENTION

Personal computers (PCs) are used commonly in the fields of business,finance, academia and industry and in the home. The prevalence of PCshas become such that users are growing increasingly dependent on theinbuilt reliability of their computers. This has resulted in usersbecoming complacent when maintaining data and system files and creating“back up” records. Furthermore, users often expect inbuilt retrievalsystems to exist which facilitate reconstruction of the records if asystem failure occurs.

In general, PCs include at least one disc drive which is used to storethe system's operating system software and data files which are createdand manipulated in everyday use. In a typical disc drive, data isrecorded in a plurality of generally circular concentric tracks on thesurfaces of one or more discs. The discs are axially aligned and mountedto a hub of a spindle motor for rotation. An array of vertically alignedread/write heads are configured to write to or read from the discsurfaces. During seek operations, the read/write heads are controllablymoved from track to track by an actuator assembly, so that data can bewritten to or read from different concentric tracks.

Along each track, data is stored in addressable sectors. A typicalformat usually includes a Master Boot Record (MBR) located at the veryfirst address, Logical Block Address 0 (LBA0), of the disc. The MBR isaccessed by the host system when it is powered or “booted” up andcontains a partition table which points to primary partitions on thedisc drive.

A disc drive can be arranged such that it contains up to four primarypartitions, each of which can be pointed to by the MBR. However, someoperating systems restrict partitioning of the disc drive such thatthere is only one primary partition. Extended partitions may be definedif necessary. Furthermore, each primary or extended partition can besubdivided into logical partitions.

The MBR contained in the primary partition references the location ofother primary partitions on the disc drive, and the next adjacentextended partition. An Extended Master Boot Record (EMBR) is located inthe first sector of each extended partition, and provides the locationof the next extended partition on the disc. Extended partitions containa boot sector (beginning in the second sector in the partition) inaddition to File Allocation Tables (FATs) which are also referenced bythe EMBR.

In addition to the partition tables, the MBR contains code which isloaded into the random access memory (RAM) of the computer using theROM-BIOS (read only memory Basic Input/Output System) and which isresponsible for the installation of the operating system when the poweris switched on. The ROM-BIOS generally contains an instruction at itsfirst address location which instructs the system to read the MBR of thefirst primary partition which subsequently results in the retrieval ofcode from the boot sector of that partition. The boot sector instructsthe computer to load the operating system software, which is generallystored in system files and data files in the primary partition, into theRAM. Control is then transferred to the operating system whichcoordinates and controls the functions of the computer's centralprocessing unit (CPU) and peripheral devices.

FATs keep track of files which are stored in partitions on the discdrive. The FATs also maintain a set of attributes for each file, such aswhether the file is one of a system data set, whether it should remainhidden in the directory display, whether it should be archived the nexttime that the disc is backed up and whether the file is read only, inaddition to a date and time stamp which stipulates when the file wascreated or last changed. When files are stored, they are placed insectors on the disc. Many files will not fit into a single sector, andthe number of sectors which is required to store a file may not beavailable in adjacent sectors in the partition. Hence the file will needto be stored in sectors which are dispersed throughout the partition indifferent tracks. Furthermore, as additional files are created, deletedand modified, they change in length and may require the use of extrasectors, or may free up one or more sectors.

The FAT provides a record of the locations of the dispersed sectorswhich are used to store each file, enabling the operating system toretrieve file data from these dispersed sectors and reconstruct thefiles accordingly. This method of file storage is spatially efficient asthe sector size can be designated such that it is not so large thatspace is frequently wasted on small files, or so small that many sectorsare required to store each file and time is wasted while the disc headscontinually move to access the next sector in the file. However, filesare often divided up into pieces and scattered all over the disc, and intime the partition becomes fragmented.

Although disc drive fragmentation and non-contiguous storage of fileclusters is usually transparent to the user, they can result in slowerfile retrieval times. This is because the read operations may beinterrupted by seek operations when the actuator assembly moves theread/write heads to another track to read the sector storing the nextfile cluster. Disc drive fragmentation therefore places an extra load onthe system as the read/write heads must make many accesses to differentlocations or to different tracks in one partition in order toreconstruct a single file. Consequently, system crashes may occur morefrequently.

Defragmentation and optimization software utilities are available withmost operating systems, but computer users who are not familiar with thephysical structure and use of their disc drives rarely consider theimportance of frequent defragmentation or disc optimization.

Occasionally, system errors occur, wherein a FAT is corrupted ordestroyed. Ordinarily, this would mean that data which was stored on thedisc would be irretrievably and permanently lost. However, theimportance of the FAT in data recovery has been recognized, and systemdevelopers have designed disc drives which maintain a copy of each FATin a partition. It has been shown that the probability of both copies ofa FAT being corrupted by the same system error is minimal; hence theduplicate storage method is sufficient for repairing damage done to apartition as a result of a system error. No such precautions have beentaken with the MBR or EMBRs.

Because each primary partition is pointed to directly by the MBR, theconsequence of a corrupt primary partition table in any partition otherthan the first primary partition is not deleterious to any primarypartition which lies outside of that partition. The remaining primarypartitions each contain their own MBR which is referenced by thepartition information in the MBR of the first primary partition. As aresult, each primary partition may be referenced independently of otherprimary partitions. If the partition table for the first primarypartition can be recovered, its file system can be restored, and in themeantime, the remaining primary partitions will still be functional.However, many operating systems, when installed on a PC, prevent thestructuring of a disc drive such that there is more than one primarypartition. Since the existence of only one primary partition means thatonly one partition can be referenced by the MBR when the system isbooted up, only one operating system can control the CPU (since a systemcannot be booted from an extended or logical partition). Software isavailable which overrides these limitations, but the regular user of aPC is not likely to use it to create more than one primary partition ontheir disc drive.

The limitation of having only one primary partition per disc drive doesnot affect most computer users in an adverse manner, as extendedpartitions can still be allocated in the disc drive, facilitatingorganized filing habits and data storage. However, the MBR cannotreference more than one extended partition directly from LBA0. Instead,the MBR is provided with a reference to the boot sector of the primarypartition and the EMBR of the first extended partition. The EMBR of thefirst extended partition provides a reference to the EMBR of the secondextended partition, which similarly provides a reference to the EMBR ofthe third (and final) extended partition.

The difficulty with the system, as it presently exists, is that thecorruption or destruction of the MBR in operating systems where only oneprimary partition is permitted results in a loss of all references toother partitions in the disc drive. That is, because of theforward-linked nature of the MBR and EMBRs, the MBR is the only recordwhich is able to determine the location of partition tables andsubsequent FATs situated anywhere on the hard drive. Although duplicatesare made of all FATs, they cannot be referenced without the MBR (or EMBRin extended partitions) which directs the operating system to thelocation of these FATs. Current systems provide backup MBRs whicheffectively reinstall the MBR using an auxiliary device such as floppydisc drive or a CD-ROM drive, but this method is ineffective if thestructure of the disc drive has been altered since the back-up MBR wascreated (e.g. if the disc drive has been reformatted and no back-upcreated). Furthermore, reinstallation of the MBR requires significantuser-intervention. Similarly, destruction of an EMBR results in loss ofall references to other extended partitions which are referred to,either directly or indirectly, by that EMBR.

What the prior art is missing is a method of maintaining partitioninformation in a disc drive that requires minimal user intervention.

SUMMARY OF THE INVENTION

A preferred embodiment of the present invention includes a method ofmaintaining partition information relating to a disc drive. The methodincludes detecting partition information which is located in the firstsector of a partition of the disc drive and determining if it is valid.The valid partition information is compared with a correspondingduplicate of the partition information which is located in a reservedarea. For valid partition information which is the same as thecorresponding duplicate of the partition information, the computercontinues with a standard booting procedure. For valid partitioninformation which is not the same as the corresponding duplicatepartition information, the method involves storing the valid partitioninformation in the reserved area. For partition information which is notvalid, the invalid partition information is replaced with correspondingduplicate partition information which is valid.

Duplicates of original partition information are created to ensure thatif original partition information is found to be invalid, a backupversion is available with which partition tables and subsequent fileallocation tables and system and data files can be recovered.

In another embodiment of the present invention, there is provided asystem for maintaining information relating to partitions in discdrives. The system includes at least one disc drive and firmware forcontrolling the initialization of the computer and its peripheraldevices. Upon application of power to the disc drive, instructionsembodied in the firmware are executed upon detection of invalidpartition information, redirecting the system to seek valid partitioninformation.

These and various other features as well as advantages whichcharacterize the present invention will be apparent upon reading of thefollowing detailed description and review of the associated drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of an exemplary disc drive in which preferredembodiments of the present invention are implemented.

FIG. 2 is a flow diagram of a process according to a preferredembodiment of the present invention.

FIG. 3 is a flow diagram illustrating an alternative embodiment of thepresent invention.

DETAILED DESCRIPTION

A disc drive 100 constructed in accordance with a preferred embodimentof the present invention is shown in FIG. 1. The disc drive 100 includesa base 102 to which various components of the disc drive 100 aremounted. A top cover 104, shown partially cut away, cooperates with thebase 102 to form an internal, sealed environment for the disc drive in aconventional manner. The components include a spindle motor 106, whichrotates one or more discs 108 at a constant high speed. Information iswritten to and read from tracks on the discs 108 through the use of anactuator assembly 110, which rotates during a seek operation about abearing shaft assembly 112 positioned adjacent the discs 108. Theactuator assembly 110 includes a plurality of actuator arms 114 whichextend towards the discs 108, with one or more flexures 116 extendingfrom each of the actuator arms 114. Mounted at the distal end of each ofthe flexures 116 is a head 118, which includes an air bearing sliderenabling the head 118 to fly in close proximity above the correspondingsurface of the associated disc 108.

During a seek operation, the track position of the heads 118 iscontrolled through the use of a voice coil motor 124, which typicallyincludes a coil 126 attached to the actuator assembly 110, as well asone or more permanent magnets 128 which establish a magnetic field inwhich the coil 126 is immersed. The controlled application of current tothe coil 126 causes magnetic interaction between the permanent magnets128 and the coil 126 so that the coil 126 moves in accordance with thewell-known Lorentz relationship. As the coil 126 moves, the actuatorassembly 110 pivots about the bearing shaft assembly 112, and the heads118 are caused to move across the surfaces of the discs 108.

The spindle motor 116 is typically de-energized when the disc drive 100is not in use for extended periods of time. The heads 118 are moved overpark zones 120 near the inner diameter of the discs 108 when the drivemotor is de-energized. The heads 118 are secured over the park zones 120through the use of an actuator latch arrangement, which preventsinadvertent rotation of the actuator assembly 110 when the heads areparked.

A flex assembly 130 provides the requisite electrical connection pathsfor the actuator assembly 110 while allowing pivotal movement of theactuator assembly 110 during operation. The flex assembly includes aprinted circuit board 132 to which head wires (not shown) are connected;the head wires being routed along the actuator arms 114 and the flexures116 to the heads 118. The printed circuit board 132 typically includescircuitry for controlling the write currents applied to the heads 118during a write operation and a preamplifier for amplifying read signalsgenerated by the heads 118 during a read operation. The flex assemblyterminates at a flex bracket 134 for communication through the base deck102 to a disc drive printed circuit board (not shown) mounted to thebottom side of the disc drive 100.

Storage space on a disc 108 may be divided into partitions. Partitioninformation that is located at the lowest logical base address (LBA0) ofa first partition of the disc drive 100 is generally referred to as theMaster Boot Record (MBR). The MBR contains a program which searches theMBR partition table for the location of the partition containing a bootsector which is to be used for initializing the operating system of thehost system. The MBR is located in a primary partition on the discdrive, which also contains the system files and data files which arenecessary for the installation of the operating system into the RandomAccess Memory (RAM). The MBR also contains a reference to all otherprimary partitions which are located on the disc drive, and the locationof the first adjacent extended partition. The first extended partitionwhose location follows the primary partition, and each subsequentextended partition thereafter, contains a partition table in the firstsector known as the extended MBR (EMBR). The EMBR provides a referenceto the boot sector and File Allocation Tables (FATs) within thatpartition in addition to the starting location of the next extendedpartition.

The Basic Input/Output System (BIOS) controls the initialization of thehost system and its peripheral devices, although in some cases it can bebypassed and other devices can be used to initialize the system. TheBIOS may be embodied in the firmware in the form of an erasableprogrammable read only memory (EPROM). The instructions embodied by thefirmware may be in the form of assembly language code which enables thefirmware to interact with the disc drive and other peripheral devicesconnected to the host system.

In a booting up process, the BIOS instructs the host system to load theoperating system from the disc drive into the RAM of the host system.This is achieved by handing control from the BIOS to a boot sector,located using the partition table which is contained in the MBR of thefirst partition on the disc drive. The system files to which the bootsector refers are then loaded into the RAM. The MBR thus contains thefirst piece of code that a host system interprets, after the BIOS hasinitiated the disc drive upon power-up.

The present invention complements existing boot procedures by assessingthe validity of the partition information, prior to the installation ofthe operating system into the RAM. The BIOS is used to execute commandswhich determine the validity of partition information contained in theMBR which is the partition record located in the very first sector ofthe first partition of the disc drive and partition informationcontained in the first sector of other partitions in the disc drive.

FIG. 2 illustrates a process in which partition information ismaintained according to preferred embodiments of the present invention.The system is powered up in step 430 and the validity of the partitioninformation which is located in the first sector of each partition onthe disc drive is determined prior to the operating system softwarebeing installed into the RAM as shown in step 432. This partitioninformation is contained in the MBR of primary partitions and the EMBRof extended partitions. The partition information is validatedpreferably by executing a subroutine which is stored in firmware, suchas the BIOS. Partition information which is not valid includesnonsensical information (for example, refers to sectors or partitionswhich do not exist) and corrupt partition information. Preferably,viruses such as boot-record infectors which are stored with thepartition information and affect the boot process can also be identifiedduring the validation process 432.

If the partition information contained in the MBR and EMBR is found tobe valid, it is then compared with duplicate partition information whichhas been stored in a reserved area, as in step 446. It is preferred thatthe reserved area is located on the disc drive, and is an area which isnot used to store system or data files in the usual everyday use of thedisc drive. Alternatively, the reserved area may be any other area whichis capable of storing partition information, including firmware. It isalso preferred that the reserved area is equally divided by the numberof partitions into which the disc drive is divided. As an alternativeembodiment, there may be partitions on the disc drive for which there isvery little partition information and as a consequence, the reservedsub-area for that partition may be less than is required for otherpartitions.

If the partition information which is located in the first sector ofeach partition matches the duplicate partition information which islocated in the corresponding reserved sub-area, system control is handedback to the BIOS which subsequently hands over to the MBR which locatesthe boot sector for the operating system and the standard boot processcontinues, as illustrated by step 448.

If the partition information which is located in the first sector of apartition is valid but does not match the duplicate partitioninformation which is located in the corresponding reserved sub-area,this suggests that the partition information in the MBR or EMBR haschanged since the last time the host system was booted. This change maybe the result of several actions. For example, the host system may havebeen booted from a floppy disc and an alternative operating system mayhave been installed resulting in a consequent change in the contents ofthe MBR. In some cases, the disc drive may have been re-formatted andthe partition information contained in the MBR or an EMBR was altered.There is also the possibility that a system error occurred, and thepartition information was corrupted.

In such cases, and in the case where any partition information is foundto be invalid, the BIOS may be programmed to instruct the user to inserta partition recovery program into a peripheral device. Recovery of thepartition information can take place and the system rebooted.

According to preferred embodiments of the present invention, the floppydisc inserted by the user is used to instruct the computer to retrievevalid duplicates of the partition information from the reserved area.

Upon retrieval of the duplicate partition information, the user ispresented with a list of the duplicate partition information and isprompted to select which partition information is to be recovered, as instep 434. The user selects the partition information to be recovered(step 436) and the duplicate partition information then replaces theinvalid partition information which was located in the MBR and/or EMBR(step 38). Recovery can be completed by overwriting the existing MBR andEMBR with the partition information taken from the reserved area 442. Inaddition, using the partition information that is retrieved from thereserved area, the system can be rebooted 444.

In alternative preferred embodiments, upon the BIOS detecting invalidpartition information in the MBR or EMBR 432, the BIOS itself executesinstructions which result in the retrieval of the duplicate partitioninformation.

Another preferred embodiment is described with the aid of the flow chartin FIG. 3. On detecting non-matching original and duplicate partitioninformation 446, a copy of the new partition information is stored inthe reserved area (as in step 550). If the reserved area is full 552, itis preferable that the oldest corresponding partition information isdeleted to create sufficient space for the new partition information554. The new partition information can then be stored in the reservedarea 556. If there is space in the reserved area for the new partitioninformation without deleting the older partition information 552, thenew partition information can be stored without first deleting an olderversion of the partition information 556.

Referring again to FIG. 2, the user is then presented with a list of theduplicate partition information which has been stored in the reservedarea (step 434). Again, this can be achieved using a commerciallyavailable partition table recovery program. Preferably, this is achievedby executing a code stored in the BIOS which presents a list of theduplicate partition information which has been stored in the reservedarea to the user so that the level of user interaction is minimized.

It is preferred that the duplicate partition information is appendedwith the date on which it was stored. This enables the user to assessthe duplicate partition information and determine which partitioninformation should be recovered and installed back into the MBR or EMBR.The user may select the earliest valid duplicate of the partition tablewhich was stored 436, since a later duplicate will most likely have beenaffected. After the user has selected the desired partition information,the selected partition information replaces the partition information inthe MBR or the EMBR 438 in the recovery process 442. The system is alsorebooted using the selected partition information 440.

If the disc drive was reformatted such that there were partitions eithercreated or destroyed, it is possible that the partition information mayhave been invalid. Thus, in one embodiment of the present invention,upon reformatting the disc drive, the duplicate partition information isupdated, ensuring that the latest version of the partition informationcan be recovered, should a system error occur which affects the originalpartition information.

This system and method provides a back up and recovery of the partitioninformation that requires relatively less user intervention.

Alternatively, embodiments of the present invention may be described asfollows:

The present invention provides for a method and system of maintainingpartition information relating a disc drive 100. When power is appliedto the disc drive 430, partition information which is located in thefirst sector of a partition of a disc drive is detected and determinedif it is valid 432. The valid partition information is compared with acorresponding duplicate of the partition information which is located ina reserved area 446. For valid partition information which is the sameas the corresponding duplicate of the partition information, the methodinvolves continuing a standard booting procedure for the computer 448.For valid partition information which is not the same as thecorresponding duplicate partition information, the method involvesstoring the valid partition information in the reserved area 456. Forpartition information which is not valid, the method involves replacingthe invalid partition information with partition information which isvalid 438.

The invalid partition information may include partition informationwhich is corrupt, missing, or has been deleteriously altered by a virus.In one embodiment, the reserved area is a dedicated area on the discwhich is reserved for the purpose of storing duplicate partitioninformation and which is equally divided by the number of partitionswhich exist on the disc drive. Alternatively, the reserved area may belocated on firmware. The duplicate partition information may be appendedwith the date on which it was created. If no space is available in thereserved area, the method can include steps of removing the oldestduplicate partition information from the reserved area 554 and storingthe newest duplicate partition information therein 556. In oneembodiment, where the partition information is not valid, it is replacedby corresponding duplicate partition information which is valid andwhich is stored in the reserved area 438. The user may be presented witha list of duplicate partition information 434, and the user selects theversion of corresponding duplicate partition information which willreplace the invalid partition information 436. The instructions whichresult in the presentation of the duplicate partition information to theuser may be contained in a storage medium which is read using aperipheral device, or firmware such as the BIOS.

It is to be understood that the foregoing disclosure is illustrativeonly, and changes may be made within the principles of the presentinvention to the full extent indicated by the broad general meaning ofthe terms in which the appended claims are expressed. Although thepreferred embodiment described herein is directed to a disc drive for apersonal computer, it will be appreciated by those skilled in the artthat the teachings of the present invention can be applied to othersystems without departing from the scope and spirit of the presentinvention.

1. A method of maintaining partition information relating a disc drive,the method comprising steps of, when the disc drive has power applied toit: (a) detecting partition information which is located in the firstsector of a partition of the disc drive and determining if it is valid;(b) comparing the valid partition information with a correspondingduplicate of the partition information which is located in a reservedarea; (c) for valid partition information which is the same as thecorresponding duplicate of the partition information, continuing astandard booting procedure for the disc drive; (d) for valid partitioninformation which is not the same as the corresponding duplicatepartition information, storing the valid partition information in thereserved area; and (e) for partition information which is not valid,replacing the invalid partition information with partition informationwhich is valid.
 2. The method according to claim 1 in which thedetecting step (a) includes determining partition information which iscorrupt, is missing, or has been deleteriously altered by a virus. 3.The method according to claim 1 further comprising a step (f) ofproviding a dedicated area on a disc of the disc drive reserved for thepurpose of storing duplicate partition information in which thededicated area is equally divided by the number of partitions whichexist on the disc drive.
 4. The method according to claim 1 furthercomprising a step (f) of providing the reserved area on firmware.
 5. Themethod according to claim 1 wherein the duplicate partition informationis appended with the date on which it was created.
 6. The methodaccording to claim 1 in which, if no space is available in the reservedarea, the step (d) further comprises steps of: (f) removing the oldestduplicate partition information from the reserved area; and (g) storingthe newest duplicate partition information therein.
 7. The methodaccording to claim 1 wherein partition information which is not valid isreplaced by corresponding duplicate partition information which is validand which is stored in the reserved area.
 8. The method according toclaim 1 wherein the user is presented with a list of duplicate partitioninformation which has been appended with the date on which it wascreated and which is stored in the reserved area, and the user selectsthe version of corresponding duplicate partition information which willreplace the invalid partition information.
 9. The method according toclaim 8 further comprising a step of executing instructions whichresults in the presentation of the duplicate partition information tothe user, in which the instructions are contained on a disc of the discdrive or on firmware.
 10. A system for maintaining information relatingto partitions in disc drives associated with a computer, the systemcomprising: at least one disc drive; firmware controlling theinitialization of the computer and its peripheral devices; andinstructions installed on the firmware which are executed upon detectionof invalid partition information, the instructions redirecting thesystem to seek valid partition information, by: (a) detecting partitioninformation which is located in the first sector of a partition of thedisc drive and determining if it is valid; (b) comparing the validpartition information with a corresponding duplicate of the partitioninformation which is located in a reserved area; (c) for valid partitioninformation which is the same as the corresponding duplicate of thepartition information, continuing a standard booting procedure for thedisc drive; (d) for valid partition information which is not the same asthe corresponding duplicate partition information, storing the validpartition information in the reserved area; and (e) for partitioninformation which is not valid, replacing the invalid partitioninformation with partition information which is valid.
 11. The systemaccording to claim 10 wherein the disc drive is divided into one or morepartitions, each partition containing partition information whichrelates to the use of sectors within that partition and the location ofat least one other partition which is located elsewhere on the discdrive.
 12. The system according to claim 10 wherein the firmwarecontrolling the initialization of the computer is a programmable readonly memory device.
 13. The system according to claim 10 wherein thefirmware controlling the initialization of the computer executes BasicInput/Output System (BIOS) software.
 14. The system according to claim13 wherein the BIOS contains instructions for determining the validityof partition information which is located in the first sector of eachpartition in the disc drive.
 15. The system according to claim 14wherein the BIOS contains further instructions which are executed upondetection of invalid partition information, the instructions comprising:(h) redirecting the system to a reserved area wherein for each partitionin the disc drive, a duplicate of valid partition information has beenstored; (i) presenting the user with duplicates of the valid partitioninformation; (j) enabling the user to select one of the duplicates ofthe valid partition information which will replace invalid partitioninformation; (k) replacing the invalid partition information with thevalid duplicate partition information which has been selected by theuser; and (l) rebooting the computer, using the replaced partitionrecords.
 16. A disc drive comprising: a disc; a set of partitioninformation describing usage allocation on the disc; and means formaintaining the set of partition information, comprising: (a) means fordetecting partition information which is located in the first sector ofa partition of the disc drive and determining if it is valid; (b) meanscomparing the valid partition information with a corresponding duplicateof the partition information which is located in a reserved area; (c)means for valid partition information which is the same as thecorresponding duplicate of the partition information, continuing astandard booting procedure for the disc drive; (d) means for validpartition information which is not the same as the correspondingduplicate partition information, storing the valid partition informationin the reserved area; and (e) for partition information which is notvalid, replacing the invalid partition information with partitioninformation which is valid.
 17. The disc drive of claim 16 in which atleast one backup copy of the set of partition information is retained inthe disc drive.
 18. The disc drive of claim 17 in which the means formaintaining the partition information further includes an executable setof instructions to replace the set of partition information with the orone of the backup copies.